1. Field of the Invention
The invention relates to a multiphase power supply device and, more particularly, to a multiphase power supply device which can automatically adjust the temperature of the voltage of each phase and measure the efficiency.
2. Description of the Related Art
Since the efficiency of a microprocessor gradually increases, it needs more power and higher transient current. However, a conventional single-phase power supply cannot meet the requirement of current systems. The current microprocessors, image and the memory systems use the multiphase power source, and the power supply device at the motherboard supports the multiphase power supply technology. The common multiphase power supply includes a four-phase or an eight-phase voltage regulator module (VRM). The multiphase power supply has an advantage of phase joint. The multiphase power supply can switch the phase in a same timing interval. Consequently, the output voltage waveform and the current can be adjusted to the average level by switching other phases in a certain interval, and when the microprocessor needs an instant high current, the multiphase power supply can provide a higher instant current via more current paths.
The efficiency of the VRM marked at the conventional motherboard is usually measured by a VRTOOL (made by Intel). The VRTOOL is a tool for virtualizing the load of the microprocessor. The VRTOOL can generate the sourcing current from the VRM, and the data including the input voltage, the input current, the output voltage and the output current is read via the pins. Then, power efficiency is obtained via the formula:
  η  =                    Vout        *        Iout                    Vin        *        Iin              .  
Wherein Vout is an output voltage, Vin is an input voltage, Iout is an output current, and Iin is an input current. Consequently, the efficiency under different loads conditions is obtained, and the highest efficiency is marked on the instruction for advertising. To measure the temperature of the VRM, an infrared camera is used to take pictures of the VRM. The current hot spot can be known via the relative temperature distribution in the pictures. However, the method cannot solve the problem of the heat accumulation. The power efficiency and the temperature of the two methods above are obtained by human operation. Thus, the measuring result is not accurate, the effect of the output power source is not good, and the power efficiency cannot automatically adjust.